there is a greater tendency among the inmates of prisons to commit offences against prison regulations in summer than in winter.  In what way is this manifest tendency to be accounted for?  If prisoners were free men living under a variety of conditions, and subject to a host of complex influences, it would be possible to adduce all sorts of causes for the existence of such a phenomenon, and it would be by no means a difficult matter to find plausible arguments in support of each and all of them.  But the almost absolute similarity of conditions under which imprisoned men live excludes at one stroke an enormous mass of complicating factors, and reduces the question to its simplest elements.  Here are a thousand men living in the same place under the same rules of discipline, occupied in the same way, fed on the same materials, with the same amount of exercise, the same hours of sleep; in fact, with similarity of life brought almost to the point of absolute identity; no alteration takes place in these conditions in summer as compared with winter, yet we find that there are more offences committed by them in the hotter season than in the colder.  In what way, except on the ground of temperature, is this difference to be explained.  The economic and social factors discussed by us in connection with the increase of crime do not here come into play.  All persons in prison are living under the same social and economic conditions in hot weather as well as in cold.  The only changes to which they are subjected are cosmical; cosmical causes are accordingly the only ones which will account adequately for the facts.  Of these cosmical causes, temperature is by far the most conspicuous, and it may therefore be concluded that the increase of prison offences in summer is attributable to the greater heat.

Seeing, then, that temperature produces these effects inside prison walls, it is only reasonable to infer that it produces similar effects on the outside world.  The larger number of offences against prison discipline which take place in the hot weather have their counterpart in the larger number of offences committed against the criminal law during the same season of the year.  The conclusions arrived at with respect to the action of season are supported by the conclusions already reached with respect to the action of climate.  In fact, both sets of conclusions support each other; both of them point to the operation of the same cause.

To any one who may still feel reluctant to admit the intimate relation between cosmical conditions and crime I would point out that suicide—­a somewhat similar disorder in the social organism—­likewise increases and diminishes under the influences of temperature.  “We cannot help acknowledging,” says Dr. Morselli, in his work on “Suicide,” “that through the whole of Europe the greater number of suicides happen in the two warm seasons.  This regularity in the annual distribution of suicide is too great to be attributed to chance or to the human